The use of security doors is becoming increasingly important, both from a safety aspect and for inhibiting unauthorised access to premises.
Latch-type locks make use of a latch bolt that is received in a frame surrounding a wing member hingedly arranged in the frame. The wing member is, conventionally, a door or window. Typically, the latch bolt is received through a striker plate mounted on the frame and can be retracted to an unlocked position to facilitate opening of the wing member.
Such latch members normally have a slanted face. If the wing member opens inwardly, the slanted face faces outwardly and this can render it relatively easy for a determined entrant to gain entry into the premises by forcing retraction of the latch bolt.
In addition, the use of only a single latch bolt further compromises the security of such a locking arrangement.
The Applicant has previously proposed the use of a plurality of latch bolts to improve the security of a security locking arrangement. Either two such latch bolts or four such latch bolts, arranged in a cruciform fashion, are mounted on the wing member. Preferably, the latch bolts are arranged on an outer surface of an operatively inner side of the wing member and this provides the advantage that the security locking arrangement can be retrofitted to an existing door. These latch bolts are also flat ended, i.e. they do not have a slanted faces.
The use of electronic access is also becoming increasingly prevalent. In addition, the Applicant has determined that the torque required to turn a key in a key lock of a security lock, arranged on an opposite side of the wing member to a handle, can be high resulting in the possibility of the key snapping with a blade of the key remaining in a barrel of the lock.
The Applicant has also determined that, particularly, with the use of electronic access facilities, an enhanced latching mechanism is required for extending the latch bolts to their locked positions upon closure of the wing member.